The holm-oak is a true oak, but an evergreen variety growing in warmer climes, with leaves that are tougher and narrower than those of a typical oak and red-shaded acorns. It thus looks somewhat like a holly tree (to which it is unrelated) and so it acquired the name 'holm-oak' or 'holly-oak'. The 'holm' element of its name evolved from an old word hollin for 'holly', and 'Hollin' was also the Mannish name for the land of Eregion. This is not a coincidence: that land was also named for the holly trees which grew there.